It is snowing in the mountains in Norway (and the Rockies) today. .Does that “prove” that global warming is not happening?
¨No, it proves that Autumn is here and Winter is coming soon.
Manmade Global warming has been going on since the Industrial Revolution and does not stop because of a 6 month slowdown in GHG emission.
There have been years with colder and years with warmer weather many places in that period, but the overall global trend has been warming. (By >1C):
and how do you prove that is from man and not naturally occurring, you cant.
The earth has been hotter and had more Co2 in the atmosphere in previous times.
Its called the weather or its the period post the ice age where the earth warms up
PS where is that thermometer thats been running since 1880?
There is one in OZ thats been running 80 years and it says no change of average temperature.
It is in an area that has less rainfall over the last 20 years, thats a fact but go 2000 miles north and you find areas that have increased rainfall.
If its not slowing down then what is causing global warming?
Not claiming it’s practical,. not even claiming exciting. To me intuitively, it seems not practical.
The question I’m asking is if it’s correct to assume that a windmill boat can’t sail upwind. If the sails of sail boat can tack upwind why can’t the blades of a turbine tack upwind as well. The blades are not moving directly upwind, they move at right angles to the wind. A beam reach so to speak.
If it’s possible in theory to sail a windmill powered boat upwind then after that it’s a question of transferring the power from the blades to the prop with sufficient efficiency.
You listen to science, not “Buddies” and conspiracy theories.
When was the CO2 concentration in the atmosphere higher?
Never according to this scientific article:
Climate Change: Atmospheric Carbon Dioxide | NOAA Climate.gov.
No, weather is what is happening today, climate is what happen over a long time.
A thermometer that has shown the same temperature for 80 years is most likely broken.
BTW: Global temperature is the average temperature over the globe, day and night, year around, not the temperature in one forsaken little place in Oz.
That is entirely as predicted; Global warming will cause less rainfall in dry areas, more in the tropical and other wet areas.(I.e. more drought and more floods)
In fact Oz could do with more and more evenly distributed rainfall and heat:
PS> Lake Eyre actually flooded in 2019:
(stepping on the soap box)
I’m what they call a climate change denier based solely of the fact that it’s being rammed down our throats for the sake of politics.
But I don’t deny immense pollution impacts climate to some degree (the degree for me is up for discussion).
From what I’ve been reading, cities like Katmandu in the Himalayas have certainly changed their microclimate due to geography, as it is surrounded by mountains and there is nowhere for air pollution to escape.
And stringed together with uncontrolled industry, large scale hydropower projects and uncontrolled metropolitan growth, the pollution alters the climate of the whole region. Every continent has equivalent examples.
For me, though, the biggest culprit is conventional industrial agriculture. It visibly changes regional climate because it lays the soil bare, and bare soil is hotter than plant-covered soil.
When you see tens of thousands of acres laid bare for the sake of one yearly crop, erosion worsens. Floods worsen. Good soil and chemicals get swept into rivers and river deltas. The fishing areas along coastlines have become poisoned by chemicals dumped thousands of miles inland.
What is the effectiveness of fishing quotas when the fish are endangered due to a failing resource management model fishing companies seemingly can’t control?
“What creates Oxygen on Earth?” is Life.
Phytoplankton is one of the main producers of oxygen and there is massive lack of information in regards to the microbiology of Earth. When there is this huge deficit in information regarding the largest oxygen providers on Earth, how can any other measure like turning engine-run ships into wind-powered ships be effective? It’s just feel-good engineering to appease the climate change bigots.
(sorry for the long post, and I’ll get off the soap box now)
All that is LOCAL climate change, not GLOBAL.
Singapore is noticeably hotter during the night now then it was 50 years ago.
That is largely because of more roads, parking lots and buildings that heat up during the day and give off heat during the night.
PS> The thousands of Air-conditions running MAY also cause very localized heating. In the 1960s Aircons were luxury, now it is in every house and flat.
I’m thinking that climates of cities get stringed like beads on a thread since they connect land, air and sea.
I think it’s correct to assume that an AOA of 0 degrees defies universal law. AFAIK iceboats can reach as close as 10 degree with virtually no drag from the surface. That would be close to what an aircraft wing is able to achieve. In the experiment listed above with the wheeled sled, I wonder what effect the rising heat from the runway surface on a 104 degree day would contribute to rotating the prop as well as the reduced rolling resistance from the high ambient temperature.
Yes there are land vessels proving a windmill blade can be geared to drive a vehicle directly up wind and downwind.
Not sure its been proven on the water yet?
with sails yes aoa zero cant do but with a windmill you can
AOA - so my analogy of the boat on a beam reach doesn’t work. But the wind turbine blades are not going to be a zero AoA because they rotate. Be more then zero.
As far as the wind-sled, my understanding is that for the downwind runs the wheels drive the prop, not the other way round as would be expected.
windmill driving wheels pushing directly upwind.
Its hard to get your head around that, thats for sure
Sorry, you can’t produce lift without a positive AOA. There has to be a pressure differential to produce lift. You can make the rotor on a helicopter spin all you want using engine power but it’s not going to rise until you introduce an angle to the blades. Basic aerodynamics.
PS. Even a monohull sailboat can sail faster than actual wind if it’s built for speed. Sailors refer to it as “creating your own wind”, the faster you go the more effective it is. I’ve never heard an explanation of how the aerodynamic forces create it. It’s a very thin slot. I would wager that it can be put in a graph and compared to actual wind speed but it’ll have to be done by someone above my pay grade. Foiling race boats get enough of a boost from it to try and spend as much time there as possible. It may provide a slim margin but in a race everything counts.
The way the sled gets a boost from the propeller is because the wheel driven gears increase the propeller’s rpm past its drag coefficient which allows it to produce a minimal amount of lift. Enough to make a slight difference. When the chain driving the prop breaks, the show’s over.
Look carefully, your thought is based on a sail at aoa and I would agree.
The wheeled vehicle is going directly upwind but the blade is not at zero aoa is it?
When a conventional sail boat is sailing in apparent as in faster ( easy downwind, lots do that) than the wind you have to look at the VMG to see if its actually going upwind faster than the wind
I’m not trying to be condescending here but there’s so much you’re missing about this, we need to go back to the basics.
A sail is a malleable airfoil. Bernoulli’s principle applies to airfoils. Look it up if you have to.
The blades would not provide lift if that was the case. What’s your point?
Wrong. VMG has nothing to do with wind or water speed. It is the speed at which a vessel is making progress with reference to a fixed point.
Here’s an example: The green boat in the diagram sails upwind on a close reach at about 45 degrees to the wind. The boat travels 7 units of distance in the time period, so we’ll say it’s boat speed was 7 units. The scale on the left shows that the boat traveled 5 units of distance upwind in the same time period. So, the boat’s VMG in this case is 5 units.
are we talking soft sails or windmill blades and Flettner rotors?
aoa versus boat speed versus wind speed all about VMG.
How do you determine what the optimum aoa is of a boat with a soft sail…VMG
You can end up with having a vmg above wind speed as is true for foiling yachts although they are not going directly upwind but they are sailing faster than the true wind speed by multiples.
The windmill powered prop driven boat apparently can go directly up wind as the land based one shows.
Ice boats also have an upwind vmg better than the wind.
With a wind turbine powered vessel the turbine axis is always aligned with wind direction even when the vessel tacks. When the vessel turns directly upwind alignment of the turbine axis remains the same as when the vessel is running with the wind abeam.
In principle there is no reason why a windmill powered boat can’t go directly upwind as can be seen with the wind-sled. In practice it’s going to depend on how efficient it is. That is if the thrust of the prop is more than the drag.
that will help lower fuel consumption
Sails, propellers, windmill blades, helicopter rotors are all airfoils and all use the same principle of pressure differential to create lift. They operate according to a common universal law. If you don’t accept that, please explain why.
Agreed
Yes, but only because it idepends on a mechanical link to the spinning wheels to overcome drag.
They can sail up to something like 10 degrees which is pretty impressive. They’re able to achieve that because of such low drag but still can’t defy gravity and sail directly upwind.
Good explanation of VMG:
